1. Field of the Invention
The present invention relates to the production of a flat yarn suitable for clothing made of natural or synthetic fiber.
2. Description of the Related Art
In the prior art, a flat yarn is produced by extruding a molten polymer from a special spinneret having a nozzle hole with a flattened rectangular profile and subjecting the spun polymer to a predetermined treatment, or by slitting a film sheet into a plurality of tapes having a proper width and subjecting the tape to a predetermined treatment. The former method, however, has drawbacks in that a large size apparatus is required for carrying out the process and it is difficult to obtain a uniform flatness of the product. Moreover, since choice of polymer kinds and configurations of the product are limited, this method is not suitable for the current tendency toward small lot and multi-kinds production. On the other hand, in the latter case, the product tends to lack stiffness when the original film sheet is thin and, conversely, to be hard and coarse in touch when the film sheet is thick, both of which result in a paper-like feeling and are unsuitable for clothing use.
For solving the above problems of the prior art, a method is proposed in which one component of a thermoplastic textured yarn is melted by a solvent and the other components thereof are adhered to each other in a flat shape by the molten component, as shown, for example, in Japanese Unexamined Patent Publication (Kokai) Nos. 53-45443 and 57-56537. According to this method, it is expected that the paper-like appearance and touch would be improved by the use of the textured yarn. In fact, however, the bulkiness of the textured yarn is much decreased due to intensive stretching thereof during the flattening and adhering processes and there remains only a micron order crimp, whereby the above drawback is still unsolved.